local $/ = '----------'.$/;
my %zips;
open (FILE,"<filename") or die "error $!";
my $teller = tell(FILE); NB need position before file read!
while (<FILE>);
  die "no zip code found record at $teller\n" unless (/Zip:\d{5}/s);
  push @{$zips{$1}}, $teller;
  $teller = tell(FILE); # FILE is optional here but a good idea!
}
open (SORTED,">newfile") or die "Can't open newfile: $!";
for (sort keys %zips) {
  for (@{$zips{$_}) {
    seek FILE, $_, 0;
    print SORTED <FILE>;
  }
}
close FILE;
close SORTED;